`RejectRouterHandler.FAIL` does not work as intended.

[chickenchickenlove]

Aremeria has three types of RejectRouterHandler.

• DISABLED
• WARN
• FAIL

However, both WARN and FAIL ultimately only produce warning logs, and the server builds successfully.
Therefore, to preserve the intended behavior of FAIL, the server build should fail when FAIL is used.

Server.builder()
                     .virtualHost("foo.com")
                     .rejectedRouteHandler(RejectedRouteHandler.FAIL)
                     .service("/foo", (ctx, req) -> HttpResponse.of("ok"))
                     .service("/foo", (ctx, req) -> HttpResponse.of("duplicate"));